Always want config before use

This caused issues in parallel builds.

shake/Main.hs

@@ -290,7 +290,7 @@ buildRules nofib@Build{..} = do
           return [ "-package-db", pkgdb, "-no-user-package-db" ]
 
     buildDepsStamp %> \out -> do
-        configs <- mapM (liftIO . getTestConfig nofib) tests
+        configs <- mapM (getTestConfig nofib) tests
         let deps = foldMap (\config -> words $ config "SRC_DEPS") configs
         -- TODO: Invoking cabal in the way we do without any package argument fails.
         root <- liftIO $ IO.makeAbsolute buildDepsRoot
@@ -323,7 +323,7 @@ buildRules nofib@Build{..} = do
             liftIO $ Ms.readFile (o <.> "compile.tsv")
 
         -- Link executable
-        compileArgs <- liftIO $ getTestCompileArgs nofib test
+        compileArgs <- getTestCompileArgs nofib test
         deps_args <- buildDepsArgs test
         () <- withResource linkerResource 1 $
             -- We pass the compiler_args as well, as we don't distinguish between link and compile time arguments
@@ -362,7 +362,7 @@ buildRules nofib@Build{..} = do
 
         -- Compile it
         let ghc_rts_args = [ "+RTS", "--machine-readable", "-t"++o++".stats" ]
-        compileArgs <- liftIO $ getTestCompileArgs nofib test
+        compileArgs <- getTestCompileArgs nofib test
         deps_args <- buildDepsArgs test
         () <- cmd compiler $ ["-Rghc-timing","-c",src,"-w","-i"++obj,"-odir="++obj,"-hidir="++obj]
                            ++ compileArgs ++ compiler_args ++ deps_args ++ ghc_rts_args
@@ -381,7 +381,7 @@ buildRules nofib@Build{..} = do
     "//Main.deps" %> \out -> do
         let test = unoutput out
         config <- readConfig' $ takeDirectory out </> "config.txt"
-        compileArgs <- liftIO $ getTestCompileArgs nofib test
+        compileArgs <- getTestCompileArgs nofib test
         deps_args <- buildDepsArgs test
         cmd_ compiler $
             [ "-w"
@@ -455,11 +455,11 @@ buildRules nofib@Build{..} = do
            <> Ms.prefix (testLabel test <> ml "run" <> ml "rts stats") rtsStats
 
 
-getTestConfig :: Nofib -> TestName -> IO (String -> String)
+getTestConfig :: Nofib -> TestName -> Action (String -> String)
 getTestConfig Build{..} test =
-    readConfig $ output </> testDir test </> "config.txt"
+    readConfig' $ output </> testDir test </> "config.txt"
 
-getTestCompileArgs :: Nofib -> TestName -> IO [String]
+getTestCompileArgs :: Nofib -> TestName -> Action [String]
 getTestCompileArgs nofib@Build{..} test = do
     config <- getTestConfig nofib test
     return $ words (config "SRC_HC_OPTS")